It has been known in the art that pictures can be produced with a stereoscopic or three-dimensional effect by providing two separate two-dimensional pictures, one of which is viewed by the left eye and the other viewed by the right eye. These stereoscopic pictures are commonly viewed by looking through a viewer or by projection onto a screen to be viewed with special polarized glasses. Examples of such stereoscopic pictures can be found in U.S. Pat. Nos. 2,144,253, 2,560,658 and 2,798,326.
The picture shown in U.S. Pat. No. 2,144,253 is typical of prior art stereoscopic pictures. While this picture is specifically designed to be looked at through a viewer, one can with practice view the picture directly by holding the picture relatively close to one's eyes while aiming one's vision at a distance so that the left eye sees the left picture and the right eye sees the right picture, the two pictures thus merging to form a stereoscopic image. This form of stereoscopic picture, however, has several disadvantages. Viewing the picture not only produces a stereoscopic image, but also produces two ghost images one on each side of the stereoscopic image. In addition, the viewer must focus his eyesight precisely on the two pictures, and if his eyes stray, he will lose the stereoscopic effect.